Living the high life

Davy Smith’s Digby Road scheme provides an intelligent mix of homes - and the tallest living wall in Europe

Housing association design guides do not have a reputation for getting architects’ creative juices flowing. Guidance on internal layouts and detailed design are, to say the least, prescriptive. But when it came to the external design and massing of the Digby Road development in Homerton, east London, concept designer Davy Smith Architects had an opportunity to make a statement that expressed confidence in the type of high-density, high-rise living called for by the brief, undaunted by the stigma it has carried in the past.

Site, brief and layout

Davy Smith Architects, who were also responsible for the planning submission, stacked up 97, mostly double-aspect, affordable and social rented flats, rising from 5 to 14 storeys in a V-shaped plan configuration, reaching a density of 1,458 habitable rooms per hectare (HRH), well over the 1,100 HRH in central London developments which is endorsed by the London Plan.

‘It’s difficult to plan a triangular site,’ says director Peter Smith. ‘The planners wanted the triangle closed off, but this would have caused overlooking problems.’ Davy Smith has provided an intelligent mix of one, two, three and four bedroom flats. This mix includes duplex flats and family units at lower level, with 10 per cent suitable for disabled residents.

The development is built over the Eurostar and HS1 tunnel, so there were restrictions on loadings. A steel frame, though lighter, would have entailed acoustic, fire protection and detailed construction problems, so concrete was used instead. ‘The tower was on the limit,’ says Davy Smith architect Rachel James, ‘so it has steel stairs and no floor screeds’.

Cladding

Davy Smith’s concept for the rainscreen terracotta cladding gives the development a distinct identity. ‘Terracotta can look quite dull,’ says Smith. ‘We addressed this problem by using lighter tile colours in the courtyard.’ Davy Smith used three slightly different standard tile colours, ranging from ochre to orange, developed by testing various facade patterns on physical models. Although local patterns appear random, there are also pronounced gradations of colour, for example on the north elevation.

What’s also unusual about the tiles is their vertical orientation, with three identical modules per floor, which coordinate with openings for windows and balconies. ‘We’re fed up with horizontal tiles,’ says Smith. ‘Vertical ties are good for corners, but most of the angled tiles had to be bonded.’ It would, of course, have been nice if single tiles could have turned the corners. ‘Typical tiles are standard, but that was about as far as it went.’ Special perforated tiles neatly provide ventilation to habitable rooms but unfortunately the tile fixings, which have a silver finish, grin through the horizontal joints.

All windows are framed by aluminium pods that help to form tidy connections with the EPDM waterproofing and the breather membrane. Windows looking on to the railway are double-glazed, as everywhere else, but have thicker glass to keep noise out.

Nearly all the flats have balconies, with concrete floors, guardings and thermal isolators where they connect to the flat slabs. ‘People cover up glass balustrades with towels,’ says Smith. The guardings are also more than the minimum height of 1,100mm required by Part K, offering more protection and privacy. As required by the conditions of the planning award, all rainwater pipes are boxed in.

Living wall

As well as conserving energy with a biomass boiler and communal heating, Digby Road also wears its green heart on its sleeve with a 220m2 west-facing living wall, that inclines three degrees from the vertical and extends from the sixth floor roof terrace to the top of the tower. ‘The system comprises HDPE cellular cassettes that contain the growing medium, and thus enabled 24,500 plants to be propagated in the nursery and installed on the building fully established,’ says Jim Quinn, an associate at A&Q Partnership, which was appointed as construction architect responsible for detailed design.

‘The modules are secured to pressure treated softwood battens, fixed and sealed to an EPDM waterproofing membrane on plywood sheathing, supported by a lightweight metal frame.’ An integral irrigation system is electronically controlled to trickle feed the planting and a drainage channel at the base collects any run-off for recycling.

There is also 350m2 of undulating sedum beds on the sixth floor terrace, which adds to the biodiversity mix.

Conclusion

Smith is critical of the interior specification and layout, which both had to follow Network Housing Group design guidelines. ‘The idea of flexible, open-plan living doesn’t exist in housing associations.’ Kitchens have fluorescent light fittings that residents are not allowed to change, which, says Smith, ‘the people from Network Housing wouldn’t put in their own homes’.

All flats meet Secured by Design standards, but this makes it very difficult for residents to negotiate the development’s restrictive lift programming and staircase door access design if they want to visit each other, which I learned the hard way when I was shown round the development by Network Housing Group’s project manager, Colin Sharratt. Nevertheless, the project team has done well to provide so many shallow, dual-aspect plans on this difficult site, although most of the architectural fun is reserved for the facade treatment.

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The Architects' Journal is the voice of architecture in Britain. We sit at the heart of the debate about British architecture and British cities, and form opinions across the whole construction industry on design-related matters